The present invention provides molecular weight markers for accurate determination of the molecular weight of glatiramer acetate, terpolymers and other copolymers. The molecular weight markers are polypeptides having identified molecular weights between about 2,000 daltons and about 40,000 daltons, and an amino acid composition corresponding to glatiramer acetate or a related copolymer. Identified molecular weights are provided by polypeptides having defined sequences. Molecular weight markers corresponding to glatiramer acetate comprise the amino acids alanine, glutamic acid, tyrosine and lysine in specific molar ratios. Molecular weight markers corresponding to related terpolymers comprise three of the four amino acids. In a preferred embodiment, the polypeptide has alanine at the N-terminus and tyrosine at the fourth position from the N-terminus. The present invention further provides a plurality of molecular weight markers for determining the molecular weight range of a copolymer composition. The plurality of molecular weight markers ideally displays linear relationships between molar ellipticity and molecular weight, or between retention time and the log of molecular weight.
Optimally, the polypeptides demonstrate biological activity similar to the copolymer from which they are derived. Polypeptides having defined molecular weights and amino acid compositions similar to glatiramer acetate optimally have therapeutic utility for the treatment of immune diseases and conditions.
Autoimmune diseases occur when an organism""s immune system fails to recognize some of the organism""s own tissues as xe2x80x9cselfxe2x80x9d and attacks them as xe2x80x9cforeign.xe2x80x9d Normally, self-tolerance is developed early by developmental events within the immune system that prevent the organism""s own T cells and B cells from reacting with the organism""s own tissues. These early immune responses are mediated by the binding of antigens to MHC molecules and presentation to T cell receptors.
This self-tolerance process breaks down when autoimmune diseases develop and the organism""s own tissues and proteins are recognized as xe2x80x9cautoantigensxe2x80x9d and attacked by the organism""s immune system. For example, multiple sclerosis is believed to be an autoimmune disease occurring when the immune system attacks the myelin sheath, whose function is to insulate and protect nerves. It is a progressive disease characterized by demyelination, followed by neuronal and motor function loss. Rheumatoid arthritis (xe2x80x9cRAxe2x80x9d) is also believed to be an autoimmune disease which involves chronic inflammation of the synovial joints and infiltration by activated T cells, macrophages and plasma cells, leading to a progressive destruction of the articular cartilage. It is the most severe form of joint disease. The nature of the autoantigen(s) attacked in rheumatoid arthritis is poorly understood, although collagen type II is a candidate.
A tendency to develop multiple sclerosis and rheumatoid arthritis is inherited. These diseases occur more frequently in individuals carrying one or more characteristic MHC class II alleles. For example, inherited susceptibility for rheumatoid arthritis is strongly associated with the MHC class II DRB1*0401, DRB 1*0404, or DRB 1*0405 or the DRB1*0101 alleles. The histocompatibility locus antigens (HLA) are found on the surface of cells and help determine the individuality of tissues from different persons. Genes for histocompatibility locus antigens are located in the same region of chromosome 6 as the major histocompatibility complex (MHC). The MHC region expresses a number of distinctive classes of molecules in various cells of the body, the genes being, in order of sequence along the chromosome, the Class I, II and III MHC genes. The Class I genes consist of HLA genes, which are further subdivided into A, B and C subregions. The Class II genes are subdivided into the DR, DQ and DP subregions. The MHC-DR molecules are the best known; these occur on the surfaces of antigen presenting cells such as macrophages, dendritic cells of lymphoid tissue and epidermal cells. The Class III MHC products are expressed in various components of the complement system, as well as in some non-immune related cells.
A number of therapeutic agents have been developed to treat autoimmune diseases, including steroidal and non-steroidal anti-inflammatory drugs, for example, methotrexate; various interferons; and certain inhibitors of prostaglandin synthesis. However, these agents can be toxic when used for more than short periods of time or cause undesirable side effects. Other therapeutic agents bind to and/or inhibit the inflammatory activity of tumor necrosis factor (TNF), for example, anti-TNF specific antibodies or antibody fragments, or a soluble form of the TNF receptor. These agents target a protein on the surface of a T cell and generally prevent interaction with an antigen presenting cell (APC). However, therapeutic compositions containing natural folded proteins are often difficult to produce, formulate, store, and deliver. Moreover, the innate heterogeneity of the immune system can limit the effectiveness of drugs and complicate long-term treatment of autoimmune diseases.
Glatiramer acetate (Copolymer 1; Cop 1; hereinafter GLAT copolymer) is a mixture of polypeptides composed of alanine, glutamic acid, lysine, and tyrosine in a molar ratio of approximately 4.6:1.5:3.6:1.0, respectively, which is synthesized by chemically polymerizing the four amino acids, forming products with average molecular weights ranging from about 4000 to about 13,000 daltons. The corresponding molar fractions are approximately 0.427 for alanine, 0.141 for glutamic acid, 0.337 for lysine and 0.093 for tyrosine, and may vary by about +/xe2x88x9210%. Related copolymers are mixtures of polypeptides composed of three (thus, xe2x80x9cterpolymersxe2x80x9d) of the four aforementioned amino acids. Copolymer 1 and the terpolymers address the innate heterogeneity of the mammalian immune system and human population and are effective for treatment of autoimmune diseases and other immune conditions. Preferred average molecular weight ranges and processes of making terpolymers are described in U.S. Pat. No. 5,800,808, which is hereby incorporated by reference in its entirety. Also contemplated by the invention are other copolymers comprised of other combinations of three, four, or five or more amino acids.
To certify a Copolymer 1 or terpolymer preparation for use in a pharmaceutical products, it is necessary to accurately determine the molecular weight distribution of the polypeptides in the preparation. One method for determining the molecular weight is chromatography on a Superose 12 column. Calibration coefficients of columns for determination of glatiramer acetate molecular weight have been determined using glatiramer acetate batches with indirectly measured molecular weights. Indirect measures have included viscosimetry and velocity-sedimentation ultracentrifugation. More recently, batches of glatiramer acetate markers have been prepared whose molecular weights were determined by multiple angle laser light scattering (MALLS).
Thus, a need exists for molecular weight markers useful as standards for determining the molecular weight distribution of copolymer compositions contemplated by the invention. Desirable molecular weight markers have defined molecular weights and physical properties which are analogous to the molecules for which molecular weight is to be determined. Ideally, there is a linear relationship between the defined molecular weights (or the log of the defined molecular weights) of the markers and a measurable physical property such as, for example, the molar ellipticity of the markers, or the retention time of the markers on a molecular sizing column.
Sequence-defined molecular weight markers that have chemical and physical characteristics similar to GLAT copolymer provide an accurate and robust calibration set for determinations of molecular weight of production batches. The present invention provides derivatives of GLAT copolymer useful as molecular weight markers for determining the molecular weight ranges of GLAT copolymer preparations and optimally having therapeutic utility for treatment of immune conditions. The invention further provides polypeptides having defined molecular weights which are derivatives of other copolymers and which are useful for determining molecular weight ranges of preparations of those copolymers. When those copolymers are therapeutically useful, the derivative polypeptides optimally have therapeutic utility. For determination of the molecular weight range of a GLAT copolymer preparation, the preferred derivative is a polypeptide having an amino acid composition corresponding approximately to GLAT copolymer and an identified molecular weight which is between about 2,000 daltons and about 40,000 daltons. The polypeptide preferably has specific molar ratios of amino acids alanine, glutamic acid, tyrosine and lysine. Moreover, in a preferred embodiment the polypeptide has alanine at the N-terminus and tyrosine at the fourth position from the N-terminus. For determination of the molecular weight of a terpolymer, the preferred derivative will have a defined molecular weight and an amino acid composition corresponding approximately to that of the terpolymer. Other copolymers are also contemplated by the invention. When determining of the molecular weight of a copolymer contemplated by the invention, the polypeptide derivative will have a defined molecular weight and an amino acid composition corresponding approximately to that of the copolymer.
The present invention further provides a plurality of molecular weight markers for determining the molecular weight of glatiramer acetate or a terpolymer or other copolymer on a molecular weight sizing column. The markers comprise two to ten or more polypeptides, each polypeptide having an identified molecular weight. When determining the molecular weight range of glatiramer acetate, a preferred plurality of molecular weight markers will have defined molecular weights from about 2,000 daltons to about 40,000 daltons, and amino acid compositions corresponding to glatiramer acetate or a selected terpolymer. In preferred embodiments, there is a linear relationship between the log molecular weight of the polypeptide molecular weight markers and either the retention time of the molecular weight markers on a sizing column or between the molecular weight of the molecular weight markers and the molar ellipticity of the molecular weight markers.
The present invention further provides pharmaceutical compositions which include a therapeutically effective amount of a polypeptide useful as a molecular weight marker for determining the molecular weight range of GLAT copolymer and consisting essentially of amino acids alanine, glutamic acid, tyrosine and lysine in molar fractions of from about 0.38 to about 0.50 alanine, from about 0.13 to about 0.15 glutamic acid, from about 0.08 to about 0.10 tyrosine, and from about 0.3 to about 0.4 lysine, and a pharmaceutically acceptable carrier.
The present invention further provides pharmaceutical compositions which include a therapeutically effective amount of a polypeptide useful as a molecular weight marker for determining the molecular weight range of a terpolymer and consisting essentially of amino acids alanine, tyrosine, and lysine in the molar fractions of from about 0.3 to about 0.6 alanine, from about 0.005 to about 0.25 tyrosine, and from about 0.1 to about 0.5 lysine, and a pharmaceutically acceptable carrier. The polypeptide is preferably substantially free of glutamic acid.
The present invention further provides pharmaceutical compositions which include a therapeutically effective amount of a polypeptide useful as a molecular weight marker for determining the molecular weight range of a terpolymer and consisting essentially of glutamic acid, tyrosine and lysine in molar fractions of from about 0.005 to about 0.300 glutamic acid, from about 0.005 to about 0.250 tyrosine, and from about 0.3 to about 0.7 lysine, and a pharmaceutically acceptable carrier. The polypeptide is preferably substantially free of alanine.
The present invention further provides pharmaceutical compositions which include a therapeutically effective amount of a polypeptide useful as a molecular weight marker for determining the molecular weight range of a terpolymer and consisting essentially of amino acids alanine, glutamic acid and tyrosine in molar fractions of from about 0.005 to about 0.8 alanine, from about 0.005 to about 0.3 glutamic acid, and from about 0.005 to about 0.25 tyrosine, and a pharmaceutically acceptable carrier. The polypeptide is preferably substantially free of lysine.
The present invention also provides pharmaceutical compositions which includes a therapeutically effective amount of a polypeptide useful as a molecular weight marker for determining the molecular weight range of a terpolymer and consisting essentially of alanine, glutamic acid and lysine, in molar fractions of from about 0.005 to about 0.6 alanine, from about 0.005 to about 0.3 glutamic acid, and from about 0.2 to about 0.7 lysine, and a pharmaceutically acceptable carrier. The polypeptide is preferably substantially free of tyrosine.
In general, pharmaceutical compositions of the invention include therapeutically effective amounts of a polypeptide which is useful as a molecular weight marker for determining the molecular weight range of a copolymer of any number (e.g., three to five or more) of amino acids. In the manner of glatiramer acetate, such a copolymer is a diverse population of sequences of the amino acids. The polypeptide useful as a molecular weight marker consists of those amino acids in molar fractions corresponding approximately to the copolymer.
The present invention further provides methods for treating and preventing immune-mediated and autoimmune diseases in a mammal which include administering a therapeutically effective amount of a molecular weight marker of the invention. In another embodiment, the method for treating immune-mediated and autoimmune diseases in a mammal further involves inhibiting proliferation of T cells involved in the immune attack. In another embodiment, the method for treating immune-mediated and autoimmune diseases in a mammal involves binding a molecular weight marker of the invention to an antigen presenting cell. In yet another embodiment, the method for treating immune-mediated and autoimmune disease in a mammal involves binding a molecular weight marker of the invention to a major histocompatibility complex class II protein which is associated with autoimmune diseases.
Autoimmune diseases contemplated by the present invention include arthritic conditions, demyelinating diseases and inflammatory diseases. For example, autoimmune diseases which can be treated by the present compositions include multiple sclerosis, rheumatoid arthritis, osteoarthritis, autoimmune hemolytic anemia, autoimmune oophoritis, autoimmune thyroiditis, autoimmune uveoretinitis, Crohn""s disease, chronic immune thrombocytopenic purpura, colitis, contact sensitivity disease, diabetes mellitus, Graves disease, Guillain-Barre""s syndrome, Hashimoto""s disease, idiopathic myxedema, myasthenia gravis, psoriasis, pemphigus vulgaris, or systemic lupus erythematosus.
Immune-mediated diseases result from undesired sensitivity of the immune system to particular foreign antigens. Examples are host-versus-graft disease (HVGD) and graft-versus-host disease (GVHD) and numerous types of delayed-type hypersensitivity (DTH).
The present compositions can be used to treat one or more of these diseases.